Centralizer

ABSTRACT

A centralizer having a hollow cylindrical body that includes an exterior surface. The centralizer includes a first centralizer blade protruding from the exterior surface of the hollow cylindrical body and has a first contact pad defined by a region of peak protrusion, wherein the first contact pad is positioned at a first vertical position on the body. The first centralizer blade is a ridge having a flat top. The centralizer includes a second centralizer blade protruding from the exterior surface of the hollow cylindrical body and has a second contact pad defined by a region of peak protrusion positioned at a second vertical position on the body, wherein the second vertical position does not vertically overlap with the first vertical position of the first contact pad.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to drilling equipment, specifically to a centralizer.

2. Description of the Related Art

A centralizer is used to ensure casing or liners which are run in a drilled hole are placed as close to the centre of the drilled hole as possible. There are many manufacturers of centralizers and different types of centralizers which include Tercel, Downhole Products (a part of Varel), TopCo, Halliburton, Weatherford, Centek and Smith (now Schlumberger). Centralizers can be of two types: spring bow or solid body.

Spring bow centralizers have a plurality of leaf springs (blades) coupling paired collars, with the leaf springs in a curved configuration when in a rest position so that they can flex inwardly (compress) during operation. Such centralizers are easy to install over stop collars or couplings and assist in improving cement flow because of the minimal use of materials in the centralizers. Such centralizers may have straight or spiral bow spring (blade) designs.

Solid body centralizers have improved stand-off over spring bow centralizers of the same gage as they are substantially rigid in operation. Such centralizers include rigid solid hollow cylindrical bodies with blades extending outwardly therefrom. Such centralizers may have straight or spiral blade designs.

Some improvements have been made in the field. Examples of references related to the present invention are described below in their own words, and the supporting teachings of each reference are incorporated by reference herein:

U.S. Pat. No. 4,794,986, issued to Langer, discloses a reticulated centralizing apparatus and methods for its use. The apparatus has a plurality of pairs of collars or cages and a plurality of springs or bows connected to and extending between the collars or cages. The bows of one pair of collars pass over one collar of another pair of collars. The bows can be alternated singly or in groups and one pair of collars may have a certain number of bows different from the number of bows associated with another pair of collars.

U.S. Pat. No. 7,096,939, issued to Kirk et al., discloses a slotted expandable centralizer. In preferred embodiments, the centralizer is adapted to be used in conjunction with slotted casing, and can expand with the casing when an expander cone is propelled through the casing.

U.S. Pat. No. 8,657,036, issued to Barron et al., discloses a tubing shoe is disclosed with a body adapted to be connected to a section of tubing to be emplaced in a wellbore and a nose provided on the body, wherein the nose includes a failure guide structure for controlling break-up of the nose upon being drilled out from inside the nose. The failure guide structure typically controls break up by limiting the maximum size of pieces of the nose broken off upon drill out, for example, by defining weakened areas of the nose which are prone to failure upon drilling. The failure guide structure can include discontinuities such as slots or bores formed or drilled into the outer surface of the nose. The failure guide structure controls the breakup of the nose in a consistent and predictable manner, and typically at a predictable stage during the drill-out process.

U.S. Pat. No. 8,584,764, issued to Nutley et al., discloses a downhole apparatus having a radially expanding portion and a support structure are described. The support structure comprises an attachment means for coupling to the apparatus and a support portion configured to be deployed from a first unexpanded condition to a second expanded condition by expansion of the apparatus. In one aspect of the invention, the downhole apparatus is expanded by exposing the swellable material to at least one predetermined fluid, and the support structure abuts the swellable material in its expanded form. A method of use and its application to a well packer, a hanging member, an anchor and a centralizing apparatus are described.

U.S. Patent Application Publication No.: 2012/0138289, by Begley et al., discloses a downhole centralizer arranged to receive a downhole tubular has a tubular body with opposed ends and is formed of plastics material A respective end ring is mounted in the or each opposed end and is formed of a plastics material having a Youngs Modulus no greater than that of the tubular body.

The inventions heretofore known suffer from a number of disadvantages which include being unreliable, being difficult to use, being ineffective, being inefficient, being slow, being expensive, being limited in use, being limited in application, being limited in adaptability, being ineffective in smaller bore regions, not working at all in smaller holes, compromising standoff, having too large an effective radius during operation, having poor flow-by area, not substantially reducing pressure on formation during flow-by as compared to typical centralizers, scratching formations, dislodging materials from formations, getting stuck in formation regions, and not substantially decreasing drag as compared to typical centralizers.

What is needed is a centralizer that solves one or more of the problems described herein and/or one or more problems that may come to the attention of one skilled in the art upon becoming familiar with this specification.

SUMMARY OF THE INVENTION

The present invention has been developed in response to the present state of the art, and in particular, in response to the problems and needs in the art that have not yet been fully solved by currently available centralizers. Accordingly, the present invention has been developed to provide an effective and efficient centralizer.

According to one embodiment of the invention, there is a centralizer that may include a hollow cylindrical body that may have an exterior surface. The centralizer may include a first centralizer blade that may be protruding from the exterior surface of the hollow cylindrical body and may have a first contact pad defined by a region of peak protrusion, wherein the first contact pad may be positioned at a first vertical position on the body. The first centralizer blade may be a ridge having a flat top.

The centralizer may include a second centralizer blade that may be protruding from the exterior surface of the hollow cylindrical body and may have a second contact pad defined by a region of peak protrusion positioned at a second vertical position on the body, wherein the second vertical position may not vertically overlap with the first vertical position of the first contact pad. The first centralizer blade and the second centralizer blade may spiral about the hollow cylindrical body. The first centralizer blade and the second centralizer blade may not be sharp. The second contact pad may overlap with no other contact pads. The centralizer may include a hollow cylindrical body that is a solid body

The centralizer may include a third centralizer blade that may be protruding from the exterior surface of the hollow cylindrical body and may have a third contact pad positioned at a third vertical position on the body, wherein the third vertical position may not completely overlap with the first vertical position and may not completely overlap with the second vertical position. The third contact pad may partially overlap vertically with each of the first contact pad and the second contact pad.

According to one embodiment of the invention, there is a centralizer that may include a hollow cylindrical body that may have an exterior surface. The centralizer may include a first centralizer blade that may have no sharp edges and may be protruding from the exterior surface of the hollow cylindrical body and may have a first contact pad defined by a region of peak protrusion, wherein the first contact pad may be positioned at a first vertical position on the body.

The centralizer may include a second centralizer blade that may have no sharp edges and may be protruding from the exterior surface of the hollow cylindrical body and may have a second contact pad defined by a region of peak protrusion positioned at a second vertical position on the body, wherein the second vertical position may not vertically overlap with the first vertical position of the first contact pad. The centralizer may include a third centralizer blade that may have no sharp edges and may be protruding from the exterior surface of the hollow cylindrical body and may have a third contact pad positioned at a third vertical position on the body, wherein the third vertical position may not completely overlap with the first vertical position and may not completely overlap with the second vertical position. The first centralizer blade, the second centralizer blade, and the third centralizer blade each may spiral about the hollow cylindrical body. The third contact pad may partially overlap vertically with each of the first contact pad and the second contact pad.

Reference throughout this specification to features, advantages, or similar language does not imply that all of the features and advantages that may be realized with the present invention should be or are in any single embodiment of the invention. Rather, language referring to the features and advantages is understood to mean that a specific feature, advantage, or characteristic described in connection with an embodiment is included in at least one embodiment of the present invention. Thus, discussion of the features and advantages, and similar language, throughout this specification may, but do not necessarily, refer to the same embodiment.

Furthermore, the described features, advantages, and characteristics of the invention may be combined in any suitable manner in one or more embodiments. One skilled in the relevant art will recognize that the invention can be practiced without one or more of the specific features or advantages of a particular embodiment. In other instances, additional features and advantages may be recognized in certain embodiments that may not be present in all embodiments of the invention.

These features and advantages of the present invention will become more fully apparent from the following description and appended claims, or may be learned by the practice of the invention as set forth hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

In order for the advantages of the invention to be readily understood, a more particular description of the invention briefly described above will be rendered by reference to specific embodiments that are illustrated in the appended drawing(s). It is noted that the drawings of the invention are not to scale. The drawings are mere schematics representations, not intended to portray specific parameters of the invention. Understanding that these drawing(s) depict only typical embodiments of the invention and are not, therefore, to be considered to be limiting its scope, the invention will be described and explained with additional specificity and detail through the use of the accompanying drawing(s), in which:

FIG. 1 is a perspective view of a centralizer, according to one embodiment of the invention;

FIG. 2 is a plurality of comparative side elevational views of a centralizer, according to one embodiment of the invention;

FIG. 3 is a top cross-sectional view of a centralizer encircled by a circular frame for illustrative purposes, according to one embodiment of the invention;

FIG. 4 is a perspective view of a centralizer, according to one embodiment of the invention; and

FIG. 5 is a side cross-sectional view of a centralizer being lowered down a hole, according to one embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

For the purposes of promoting an understanding of the principles of the invention, reference will now be made to the exemplary embodiments illustrated in the drawing(s), and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended. Any alterations and further modifications of the inventive features illustrated herein, and any additional applications of the principles of the invention as illustrated herein, which would occur to one skilled in the relevant art and having possession of this disclosure, are to be considered within the scope of the invention.

Reference throughout this specification to an “embodiment,” an “example” or similar language means that a particular feature, structure, characteristic, or combinations thereof described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, appearances of the phrases an “embodiment,” an “example,” and similar language throughout this specification may, but do not necessarily, all refer to the same embodiment, to different embodiments, or to one or more of the figures. Additionally, reference to the wording “embodiment,” “example” or the like, for two or more features, elements, etc. does not mean that the features are necessarily related, dissimilar, the same, etc.

Each statement of an embodiment, or example, is to be considered independent of any other statement of an embodiment despite any use of similar or identical language characterizing each embodiment. Therefore, where one embodiment is identified as “another embodiment,” the identified embodiment is independent of any other embodiments characterized by the language “another embodiment.” The features, functions, and the like described herein are considered to be able to be combined in whole or in part one with another as the claims and/or art may direct, either directly or indirectly, implicitly or explicitly.

As used herein, “comprising,” “including,” “containing,” “is,” “are,” “characterized by,” and grammatical equivalents thereof are inclusive or open-ended terms that do not exclude additional unrecited elements or method steps. “Comprising” is to be interpreted as including the more restrictive terms “consisting of” and “consisting essentially of.”

FIG. 1 is a perspective view of a solid body centralizer, according to one embodiment of the invention. There is shown a centralizer 10 including a solid hollow cylindrical body 12 showing a first centralizer blade 16 and a second centralizer blade 24. There is a third centralizer blade (not shown) obscured by the solid body of the centralizer in this view. The illustrated centralizer 10 has a more reduced effective diameter than other centralizers. This helps the centralizer to work through narrowed regions in drill holes (bore holes) and also reduces flow-by pressure.

The illustrated centralizer 10 has vertically offset touch points around the exterior of the centralizer. Specifically, the three blades each include a region of highest protrusion from the hollow cylindrical body and each of these regions is disposed at a particular “height” or vertical displacement from the “bottom” or end of the hollow cylindrical body. The regions do not fully overlap, one with the other, and therefore are “offset.” Thus, when interacting with the drill hole, the centralizer 10 will have a smaller effective radius, while still providing solid offset. This combines many of the benefits that are found separately in solid body centralizers and spring bow centralizers without the corresponding negative features of each. Wherein features more like a solid body centralizer are desired (e.g. stronger offset) the hollow cylindrical body may be a solid body. Wherein features more like a spring bow centralizer are desired, the blades may be leaf springs coupled between paired collars, yet still have offset regions of peak protrusion. It is expected that the solid body version will be most often the desired configuration.

Further, wherein the centralizer 10 has a leading touch point, it focuses the weight of the centralizer in one asymmetric location, which may cause the centralizer to twist and turn as you work it through a difficult region of the drill hole.

Illustrated are three pads that are larger and thicker than typical blades of a centralizer. The illustrated blades also do not have sharp edges (e.g. sharply cornered) to catch on the walls but instead include edgeless blades that slides/glides over them. The illustrated blades have gradually rounded edges. It may be that there is a centralizer that has no sharp edges at all. It may be that there is a centralizer that has no sharp edges on surfaces that are likely to come into contact with formation during operation. Such may include a centralizer that may be vertically asymmetric, with sharp trailing edges that do not come into contact with a formation when the centralizer is lowered into position, but may come into contact with formation if the centralizer is every lifted upwardly/outwardly of a bore hole.

The illustrated centralizer 10 includes a hollow cylindrical body 12 having an exterior surface 14. The centralizer 10 includes a first centralizer blade 16 protruding from the exterior surface 14 of the hollow cylindrical body 12. The first centralizer blade 16 includes a first contact pad 18 defined by a region of peak protrusion 20, wherein the first contact pad 18 is positioned at a first vertical position on the body. The contact pad is illustrated as a rectangular region, which may illustrate a flattened region or it may merely provide a graphical representation of a shallowly rounded region of greatest protrusion. The illustrated first centralizer blade 16 includes a ridge having a flat top.

The illustrated centralizer 10 also includes a second centralizer blade 24 protruding from the exterior surface 14 of the hollow cylindrical body 12. The second centralizer blade 24 includes a second contact pad 26 defined by a region of peak protrusion positioned at a second vertical position on the body 12. The illustrated first centralizer blade 16 and the second centralizer blade 24 spiral about the hollow cylindrical body 12. The illustrated first centralizer blade 16 and the second centralizer blade 24 are not sharp.

The first centralizer blade 16 and the second centralizer blade 24 are disposed offset from each other, to further help the centralizer 10 down a drill hole during use. The first centralizer blade 16 and the second centralizer blade 24 are not sharp and include a flat top on a ridge. This configuration allows the centralizer to easily maneuver down a drill hole without the blades being caught or stuck in a tight region of the drill hole.

There may be a centralizer having a plurality of blades and/or touch pads, which may be more than three blades and/or touch pads. There may be multiple tail touch pads that may be spaced close together. It may be that a blade is wider than its maximum protrusion and that a ratio of the width (e.g. average width, maximum width) to its maximum protrusion may be greater than about 1.5:1, 2:1, 3:1, 4:1, 5:1, and/or 6:1.

According to one embodiment of the invention, there is a centralizer that includes a unique blade placement, which provides a much reduced hydraulic diameter without compromising stand-off. The centralizer also includes placing the touch-points off centre, which implies that the centralizer is more easily worked through obstructions in the drill hole or wellbore as compared to other centralizers. The centralizer includes wider blade profiles, which enable the gradual smoothening/drop of the blade profile to reduce digging into the formation; the blade profile allows the centralizer to glider/slide over it if rotation is actuated or required. The centralizer includes a single blade leading edge, which the initial pass through diameter and the final diameter of the centralizer are smaller than the gauge diameter created by the two or three blades. In theory this should make running in and out of the drill hole, dislodging or breaking through obstructions a lot easier as the centralizer gets through a reduced hole diameter and with circulation, rotation and/or reciprocation the obstruction can be circulated out or dislodged. The centralizer includes three blades, wherein the flow-by-area is enhanced and the spiral blades should enable uniform deposition of cement across the wellbore even in highly inclined/horizontal boreholes. However, since the design closely resembles that of a standard spiral stabiliser, one may infer from simulations carried out by European Drilling Projects on how spiral stabilisers induce “balling”.

FIG. 2 is a plurality of comparative side elevational views of a centralizer, according to one embodiment of the invention. There is shown a plurality of views of a centralizer 10, each showing a different view of the associated centralizer blades in order to illustrate the relative vertical displacement of the blades' respective regions of maximum protrusion and the overlap thereof as illustrated by dotted lines 21, 23, 25, and 27, which illustrate, respectively, (21) the bottom of first contact pad 18, (23) the top of the third contact pad 32, (25) the top of the second contact pad 26, and (27) the bottom of the third contact pad 26.

The illustrated centralizer 10 includes a hollow cylindrical body having an exterior surface. The centralizer 10, on the left, includes a first centralizer blade 16 having no sharp edges and is protruding from the exterior surface of the hollow cylindrical body. The first centralizer blade 16 includes a first contact pad 18 defined by a region of peak protrusion, wherein the first contact pad 18 is positioned at a first vertical position (as defined by the region between the bottom and top of the contact pad) on the body.

The illustrated centralizer 10, in the middle, includes a second centralizer blade 24 having no sharp edges and is protruding from the exterior surface of the hollow cylindrical body. The second centralizer blade 24 includes a second contact pad 26 defined by a region of peak protrusion positioned at a second vertical position on the body, wherein the second vertical position 28 does not vertically overlap with the first vertical position of the first contact pad 18.

The illustrated centralizer 10, on the right, includes a third centralizer blade 30 having no sharp edges and is protruding from the exterior surface of the hollow cylindrical body. The third centralizer blade 30 includes a third contact pad 32 positioned at a third vertical position 34 on the body, wherein the third vertical position 34 does not overlap with the first vertical position and does not completely overlap with the second vertical position. If the third contact pad where larger and/or disposed higher at its top, it would partially overlap with the first vertical position of the first contact pad. The first centralizer blade 16, the second centralizer blade 24, and the third centralizer blade 30 each spiral about the hollow cylindrical body. The illustrated third contact pad 32 partially overlap vertically with the second contact pad 26, but not with the first contact pad 18. If the second contact pad 26 were disposed in a lower position and/or smaller, it may not overlap at all with the third contact pad 32, and in such a case (everything else being the same), none of the contact pads would overlap with each other at all. Such a configuration would provide the lowest effective radius of the centralizer.

FIG. 3 is a top cross-sectional view of a centralizer encircled by a circular frame 14 for illustrative purposes, according to one embodiment of the invention. The illustrated centralizer 10 includes a hollow cylindrical body 12 having an exterior surface, wherein a first centralizer blade 16 and a second centralizer blade 24 are disposed thereon.

The illustrated centralizer 10 includes a hollow cylindrical body 12 having an exterior surface. The centralizer 10 includes a first centralizer blade 16 protruding from the exterior surface of the hollow cylindrical body 12. The illustrated centralizer 10 also includes a second centralizer blade 24 protruding from the exterior surface of the hollow cylindrical body 12 in an amount greater than that of the first centralizer blade 16 at the vertical point of cross-section illustrated, thus illustrating potential overlap between first and second contact pads of the first and second blades. The framing circle 14 assists the viewer of FIG. 3 in observing the difference in protrusions of the first and second blades. There is no third blade protrusion (see 31) illustrated at this particular vertical point of cross-section, illustrating that the third blade of the centralizer of FIG. 3 does not have any overlap with the first and second contact pads.

FIG. 4 is a perspective view of a centralizer, according to one embodiment of the invention. There is shown a centralizer 10 including a hollow cylindrical body 12 having a first centralizer blade 16 and a second centralizer blade 24.

The illustrated centralizer 10 includes a hollow cylindrical body 12 having an exterior surface 14. The centralizer 10 includes a first centralizer blade 16 protruding from the exterior surface 14 of the hollow cylindrical body 12. The first centralizer blade 16 includes a first contact pad 18 defined by a region of peak protrusion, wherein the first contact pad 18 is positioned at a first vertical position on the body. The illustrated first centralizer blade 16 includes a ridge having a flat top with sharp edges.

The illustrated centralizer 10 also includes a second centralizer blade 24 protruding from the exterior surface 14 of the hollow cylindrical body 12. The second centralizer blade 24 includes a second contact pad 26 defined by a region of peak protrusion positioned at a second vertical position on the body 12. The illustrated first centralizer blade 16 and the second centralizer blade 24 spiral about the hollow cylindrical body 12. The illustrated first centralizer blade 16 and the second centralizer blade 24 are not sharp.

FIG. 5 is a side cross-sectional view of a centralizer being lowered down a hole, according to one embodiment of the invention. There is shown a centralizer 10 being lowered down a drill hole 45.

The illustrated centralizer 10 is of a spring bow type and has a more reduced hydraulic diameter than other centralizers because of offset protrusions 52 and 54. This configuration helps the centralizer 10 to work through narrowed regions of a drill hole 45. The centralizer 10 has an offset touch points around the exterior of the centralizer; wherein the centralizer 10, when interacting with the drill hole 45 will have a smaller effective radius. Further, wherein the centralizer 10 has a leading touch point, it focuses the weight of the centralizer in one asymmetric location, which will cause the centralizer 10 to twist and turn as the centralizer 10 works through a difficult region of the drill hole 45. There are three pads that are larger and thicker than typical blades of a centralizer and do not have sharp edges to catch on the walls but instead slides/glides over them.

STATEMENTS OF THE INVENTION

1. A centralizer, comprising:

a) a hollow cylindrical body having an exterior surface;

b) a first centralizer blade protruding from the exterior surface of the hollow cylindrical body and having a first contact pad defined by a region of peak protrusion, wherein the first contact pad is positioned at a first vertical position on the body; and

c) a second centralizer blade protruding from the exterior surface of the hollow cylindrical body and having a second contact pad defined by a region of peak protrusion positioned at a second vertical position on the body, wherein the second vertical position does not vertically overlap with the first vertical position of the first contact pad.

2. The centralizer of claim 1, further comprising a third centralizer blade protruding from the exterior surface of the hollow cylindrical body and having a third contact pad positioned at a third vertical position on the body, wherein the third vertical position does not completely overlap with the first vertical position and does not completely overlap with the second vertical position. 3. The centralizer of claim 2, wherein the third contact pad partially overlaps vertically with each of the first contact pad and the second contact pad. 4. The centralizer of any preceding Claim, wherein the first centralizer blade and the second centralizer blade spiral about the hollow cylindrical body. 5. The centralizer of any preceding Claim, wherein the first centralizer blade and the second centralizer blade are not sharp. 6. The centralizer of any preceding Claim, wherein the first contact pad overlaps with no other contact pads. 7. The centralizer of any preceding Claim, wherein the first centralizer blade is a ridge having a flat top and the hollow cylindrical body is a solid body. 8. A centralizer of any of the preceding Claims wherein the first and second centralizer blades have no sharp edges. 9. The centralizer of claim 8, when dependent upon claim 2, wherein the third centralizer blade has no sharp edges. 10. The centralizer of claim 9, wherein the first centralizer blade, the second centralizer blade, and the third centralizer blade each spiral about the hollow cylindrical body. 11. The centralizer of claim 10, wherein the third contact pad partially overlaps vertically with each of the first contact pad and the second contact pad. 12. A centralizer according to claim 9, wherein the third contact pad partially overlaps vertically with each of the first contact pad and the second contact pad.

It is understood that the above-described embodiments are only illustrative of the application of the principles of the present invention. The present invention may be embodied in other specific forms without departing from its spirit or essential characteristics. The described embodiment is to be considered in all respects only as illustrative and not restrictive. The scope of the invention is, therefore, indicated by the appended claims rather than by the foregoing description. All changes which come within the meaning and range of equivalency of the claims are to be embraced within their scope.

For example, although the FIGS. 1-4) illustrate centralizers having three blades, it is understood that centralizers may have a number of blades other than three.

Additionally, although the figures illustrate centralizers of specific proportions with overlapping regions of particular sizes and overlap regions, the variations of such sizes and proportions, except where noted otherwise, are plethoric.

Finally, it is envisioned that the components of the device may be constructed of a variety of materials, including but not limited to metals, ceramics, wood, plastics, rubbers and the like and combinations thereof.

Thus, while the present invention has been fully described above with particularity and detail in connection with what is presently deemed to be the most practical and preferred embodiment of the invention, it will be apparent to those of ordinary skill in the art that numerous modifications, including, but not limited to, variations in size, materials, shape, form, function and manner of operation, assembly and use may be made, without departing from the principles and concepts of the invention as set forth in the claims. Further, it is contemplated that an embodiment may be limited to consist of or to consist essentially of one or more of the features, functions, structures, methods described herein. 

What is claimed is:
 1. A centralizer, comprising: a) a hollow cylindrical body having an exterior surface; b) a first centralizer blade protruding from the exterior surface of the hollow cylindrical body and having a first contact pad defined by a region of peak protrusion, wherein the first contact pad is positioned at a first vertical position on the body; and c) a second centralizer blade protruding from the exterior surface of the hollow cylindrical body and having a second contact pad defined by a region of peak protrusion positioned at a second vertical position on the body, wherein the second vertical position does not vertically overlap with the first vertical position of the first contact pad.
 2. The centralizer of claim 1, further comprising a third centralizer blade protruding from the exterior surface of the hollow cylindrical body and having a third contact pad positioned at a third vertical position on the body, wherein the third vertical position does not completely overlap with the first vertical position and does not completely overlap with the second vertical position.
 3. The centralizer of claim 1, wherein the first centralizer blade and the second centralizer blade spiral about the hollow cylindrical body.
 4. The centralizer of claim 1, wherein the first centralizer blade and the second centralizer blade are not sharp.
 5. The centralizer of claim 1, wherein the first contact pad overlaps with no other contact pads.
 6. The centralizer of claim 1, wherein the first centralizer blade is a ridge having a flat top and the hollow cylindrical body is a solid body.
 7. The centralizer of claim 2, wherein the third contact pad partially overlaps vertically with each of the first contact pad and the second contact pad.
 8. A centralizer, comprising: a) a hollow cylindrical body having an exterior surface; b) a first centralizer blade having no sharp edges and protruding from the exterior surface of the hollow cylindrical body and having a first contact pad defined by a region of peak protrusion, wherein the first contact pad is positioned at a first vertical position on the body; and c) a second centralizer blade having no sharp edges and protruding from the exterior surface of the hollow cylindrical body and having a second contact pad defined by a region of peak protrusion positioned at a second vertical position on the body, wherein the second vertical position does not vertically overlap with the first vertical position of the first contact pad.
 9. The centralizer of claim 8, further comprising a third centralizer blade having no sharp edges and protruding from the exterior surface of the hollow cylindrical body and having a third contact pad positioned at a third vertical position on the body, wherein the third vertical position does not completely overlap with the first vertical position and does not completely overlap with the second vertical position.
 10. The centralizer of claim 9, wherein the first centralizer blade, the second centralizer blade, and the third centralizer blade each spiral about the hollow cylindrical body.
 11. The centralizer of claim 10, wherein the third contact pad partially overlaps vertically with each of the first contact pad and the second contact pad.
 12. A centralizer, comprising: a) a hollow cylindrical body having an exterior surface; b) a first centralizer blade having no sharp edges and protruding from the exterior surface of the hollow cylindrical body and having a first contact pad defined by a region of peak protrusion, wherein the first contact pad is positioned at a first vertical position on the body; c) a second centralizer blade having no sharp edges and protruding from the exterior surface of the hollow cylindrical body and having a second contact pad defined by a region of peak protrusion positioned at a second vertical position on the body, wherein the second vertical position does not vertically overlap with the first vertical position of the first contact pad; and d) a third centralizer blade having no sharp edges and protruding from the exterior surface of the hollow cylindrical body and having a third contact pad positioned at a third vertical position on the body, wherein the third vertical position does not completely overlap with the first vertical position and does not completely overlap with the second vertical position, and wherein the third contact pad partially overlaps vertically with each of the first contact pad and the second contact pad. 